On 25Jan15, John Heidemann allegedly wrote: > I think these statements are both overly strong. They both suggest > that careful signaling is required before deploying DNS over TCP with > pipelining or > persistence.
If virtually no initiators send multiple requests then your conclusion seems reasonable. > Only if you want 8% of your queries to fail. > http://users.isc.org/~marka/ts/alexa.optfail.html > > > That's harm on the initiator side. But the harm should be a lot less than the proportion of servers exhibiting the problem, yes? First off there is the matter of proportion of queries that actually go to failing servers. Even with the top 1,000 domains, most of it is long tail. Second the cost should be amortized across all queries, not just the first few to a given server. I'm assuming that these yet-to-be-implemented out-of-order initiators may well have heuristics that determine whether a TCP connection is worth it or not. I'm also assuming that they'll have to track their currently active TCP connections. With this sort of machinery in place it's not a huge additional burden to track failed connections of high-occurrence servers for a reasonably long time period. In other words, the cost of detecting a non-compliant server could reasonably be amortized across many queries. The net harm will never be zero, but it should be approaching it. Also, the motivation to improve the situation resides with the person most capable of making changes - the owner of the domain. That's a nice alignment of interests. Mark. _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
